At the same time, it began clamping down on third-party applications that offer users alternative ways to view their Twitter stream. Most notably, said users would no longer be able to view their stream of tweets on its website, though they can still post tweets from LinkedIn.

Some developers balked, believing Twitter might soon shut them out, too.

"The mistake we all made with Twitter, me too, was to think a corporate API could act like an open protocol," software developer Dave Winer .

Kwasi Frye, of Clearly Innovative, a software design and development company, said Twitter was sending signals that "it is not going to continue to be supportive of developers mimicking the Twitter platform -- or pretty much anything they're doing with the API."

The responses stem in part from the difficult relationship Twitter has had lately with its developers. After its launch in 2006, Twitter encouraged developers to get creative with its platform. Some of its core features, including retweeting, originated outside the company. Third-party applications such as TweetDeck, HootSuite, Echofon and CoTweet proliferated.